Transferring condensed liquids to a storage container



Nov. 28, 1967 J. VAN DER STER ETAL 3,

TRANSFERRING CONDENSED LIQUIDS TO A STORAGE CONTAINER 5 Sheets-Sheet 1,

Filed April 1, 1965 TIMER CONTROLLED 3 CbNDENS ATION l SPACE CONDENSATECONTAINER OR RECEPTACLE GAS REFRIGERATOR STORAGE CONTAINER AGENT ELM/L 8Nov. 28, 1967 J. VAN DER STER ETAL 3,

I TRANSFERRING CONDENSED LIQUIDS TO A STORAGE CONTAINER Filed April 1,1965 5 Sheets-Sheet 2 TIMER CONTROLLED 2 3CONDENSATION I SPACE 5 ICONDENSATE CONTAINER 0R 8 1 EcEPTAcLE 4 I 1 sA's REFRIGERATOR OPENEDSIMULTANEOUSLY 15 TO DISCHARGE TO CONTAINER STORAGE CONTAINER FIG.3

JOHANNES VAN DEQQTEfi GERARDUS J.HAARHU|S EARN J.TU|N

Nov. 28, 1967 J. VAN DER STER ETAL 3,354,664

TRANSFERRINGCONDENSED LIQUIDS TO A STORAGE CONTAINER Filed April 1, 19655 Sheets-Sheei 3 TIM/ER CONTROLLED I CONDENSATION 2 8 3 SPACE CONDENSATE3 I CONTAINER OR BECEPTACLE 4 2o J t 1 GAS I REFRIGERATOR 8 OPENEDSIMULTANEOUSLY CONTAINER 5 1s SLIGHTLY ABOVE THAT IN CONTAINER 7 WHENPRESSURE IN I STORAGE CONTAINER FIG. 5

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SHANNES VAN DER w ERN RARDUH. HAARHUI S gA RM .T N

AGEN

Nov. 28, 1967 J. VAN DER STER ETAL 3,354,664

TRANSFERRING CONDENSED LIQUIDS TO A STORAGE CONTAINER Filed April 1,1965 5 Sheets-Sheet 4 TIMER CONTROLLED R 3 couoiz fi lifiow I 2 SPACECONDENSATE 1 V 7 5 i CONTAINER OR 3 RECEPTACLE 4% \v 1 GAS I 20 \l 21REFRIGERATOR 2/.

STORAGE CONTAINER res JOHANN s VAND E GERARDU J-HAARHUIS HARM J.TU|N' BYM K \-R AGENT Nov. 28, 1967 J. VAN DER sTER ETAL 3,354,664

TRANSFERRING CONDENSED LIQUIDS TO A STORAGE CONTAINER Filed April 1,1965 5 Sheets-Sheet 5 GAS REFRIGERATOR 38 (i 50 49 I GAS LIQUIFIED INLETGAS OUTLET JOHANNES' VAN TOR; GERARDUS J.HAARHUIS H RM J.TUIN

BY v

AGENT United States Patent 3,354,664 TRANSFERRING CONDENSED LIQUIDS T0 ASTORAGE CONTAINER Johannes van der Ster, Gerardus Johannes Haarhuis, andHarm Jan Tuin, Emmasingel Eindhoven, Netherlands, assignors to NorthAmerican Philips Company Inc., New York, N.Y., a corporation of DelawareFiled Apr. 1, 1965, Ser. No. 444,634 Claims priority, applicationNetherlands, Apr. 11, 1964, 64-3,952 6 Claims. (CI. 62-37) ABSTRACT OFTHE DISCLOSURE A method and device for condensing gas for a certainperiod of time under high pressure in a low temperature device whereuponthe inlet is closed and the gas is further cooled down to a temperaturecorresponding with the vapor pressure which is equal or lower than thepressure prevailing in the liquefied gas storage space.

The invention relates to a method of liquefying a gas and to a devicefor performing the said method.

In a known method of the present type, a gas under pressure is suppliedto a space which is cooled to the condensation temperature of the gas inquestion associated with that pressure. This space is preferably cooledby means of a cold-gas refrigerator. In that space the gas is condensed,after which this condensed gas is conducted away.

A drawback of this known method, in which gas is continuously condensedand conducted away, is that during the conducting away of the liquefiedgas there has to be expanded from the pressure at which the condensationtakes place, through an expansion valve to atmospheric pressure. In thiscase again a great part of the liquid volatilizes which adverselyinfluences the production. The percentage of volatilized liquid may insome cases be even 30% for example, in the case of hydrogen gas which isliquefied under a pressure of 8 atmospheres.

In known devices the volatilized liquid is conducted through a heatexchanger where it is heated again to room temperature in countercurrent with the gas to be condensed. This gives an improvement of theyield with respect to the above method, but it has the disadvantage thatit requires a heat exchanger which in general is com plicated andexpensive.

A further drawback of this known type of devices is that the gas to becondensed must be of high purity since otherwise the channels in theheat exchanger and in the expansion valve, which, in general, are verynarrow, can be clocked by the contamination-s.

It is the object of the invention to render the above complicated andexpensive heat exchanger and the expansion valve superfluous in whichall the same the 3,354,664 Patented Nov. 28, 1967 "ice for liquefyinggases, for example air, oxygen, nitrogen, hydrogen, helium, etc, with abetter yield then could be obtained so far.

A further advantage of the said method is that the condensate is forcedinto the storage container by the gas under pressure, As a result ofthis it has become possible to cool the condensate, during the continuedcooling, to a very low temperature and pressure and it is even possibleto continue the cooling to such an extent that the pressure of thecondensate lies below the pressure in the storage container while allthe same the transport of the condensate to the container can take placein a comparatively short period of time. This will be further explainedin the description of the figures.

The invention further relates to a device which is suitable forperforming the method according to the invention. This device isparticularly suitable for heavier gases, for example, oxygen andnitrogen. The device according to the invention comprises at least onerefrigerator, the cold part of which is arranged in a condensation spaceto which space are connected an inlet pipe for gas under pressure and anoutlet pipe for liquefied gas. This device is characterized in that inthe inlet and outlet pipes controllable cocks are provided in which inthe outlet pipe also a check valve is operative which checks the flowout of the storage container to the condensation space, the devicecomprising a control device, which, when the cock in the outlet pipe isclosed, keeps the cock in the inlet pipe opened for a given period oftime or after a given quantity of condensate is present in the device,after which the control device closes the cock in the inlet pipe and therefrigerator reduces the pressure of the condensate by continued coolinguntil this pressure is lower than the pressure in the storage container,after which the control device opens the cooks in the inlet and outletpipes.

So in this case the condensate enters the storage container in asupercooled condition. This has the advantage that the losses ofinsulation which always occur cause no evaporation of condensate.Consequently little or no vapour is blown olf out of the storagecontainer so that substantially no gas loss occurs.

The expression supercooled condition of the condensate is understood tomean in the present application that the temperature of this condensateis lower than the boiling point temperature of the condensate at thepressure prevailing in the storage container.

A difiiculty in this device is that during forcing the condensate out ofthe condensation space to the storage container the possibility existsthat simultaneously with the last quantity of condensate also a quantityof gas under high pressure disappears to the storage container and fromthere is blown off and is to be considered as a loss.

favorable condition of liquefying gas under high pressure is maintainedwhich consequently can take place at a higher temperature, at whichtemperature the required cold can in general be supplied moreefiiciently.

The method according to the invention is characterized The methodaccording to the invention may be used In order to overcome thisdifliculty a further embodiment of the device according to the inventionis characterized in that the outlet pipe empties at a low point in thecondensation space and that opposite to the outlet a float is arrangedwhich is capable of closing this outlet when the liquid has fallen belowa given level.

It has been found possible to use a float for these heavier gases. Thisfloat ensures that, when the liquid level has fallen below a givenvalue, the outlet of the liquid outlet pipe is closed so that the gasunder pressure can no longer flow to the storage container. As a resultof this losses of gas, which often is expensive, is prevented.

A further favorable embodiment of the device according to the inventionis characterized in that the float has thin walls and comprises a pipewhich is open at both ends, one end of the said pipe emptyingsubstantially at the bottom of the hollow float and the other endextend- ,ng upwards through such a distance that the upper end alwaysprojects above the liquid in the condensation space. Therefore in thisdevice the same pressure will prevail in the float and in thecondensation space, so that the walls of the float are not subjected tohigh pressure- ;litferences. As a result of this, the walls of the floatmay be thin so that it has a light-weight construction and acomparatively small float will be suificient. A further advantage ofthis construction is that, when condensate collects in the float, thiscondensate is pumped back again to the condensation space through theopen pipe out of the float during the period that the pressure in thecondensation space is being reduced.

In the case of liquefied gases, for example, hydrogen and helium, whichhave a very low specific weight, it is no longer practical to use afloat of reasonable proportions. In order to condense these valuablegases also with the method according to the invention without greatlosses occuring because an inadmissable quantity of these valuable gasesdisappears to the storage container with the last condensate, afavorable embodiment of the method in accordance with the invention ischaracterized in that controllable cocks are provided in the inlet andoutlet pipes, and a check valve being provided, if desired, in theoutlet pipe. The controllable cock itself operating as a check valve, ifdesired, which prevents flow of medium from the storage container to thecondensation space, a circulating pipe being connected in parallel withthe cock in the inlet pipe, in which circulating pipe a flow resistanceand a further controllable cock are provided, which flow resistance hassuch a passage that the stream of gas flowing through it at the fullpressure difference between the gas inlet pipe and the storage containersubstantially corresponds to the gas current which the coldgasrefrigerator can condense at a pressure which is substantially equal tothe pressure in the storage container. The present device comprising acontrol device which, when the cock in the outlet pipe is closed, keepsthe cock in the inlet pipe opened for a given period of time or until agiven quantity of condensate is present in the device, after which thecontrol device closes the cock in the inlet pipe and the refrigeratorreduces the pressure of the condensate by continued cooling until saidpressure lies somewhat above the pressure in the storage container,after which the control device opens the cock in the outlet pipe and thefurther cock. Although this device comprises no float, it has all thesame been prevented that an inadmissible quantity of these valuablegases is lost. The operation and advantages of this device will befurther explained in the description of the figures.

A further favorable embodiment of the above device according to theinvention is characterized in that in the circulating pipe between theflow resistance and the further cock a further container is provided,the control device opening the cock in the outlet pipe and the furthercock in the circulating pipe only when the pressure in the condensationspace is lower than the pressure in the storage container. Therefore inthis case there is the possibility of supercooling the liquid.

In order that the invention may readily be carried into effect, a fewdevices for liquefying gases will now be described in greater detailwith reference tothe diagrammatic drawings in which FIG.-1diagrammatically shows a device for liquefying gases;

FIG. 2 shows the operation of the device shown in FIG. 1 in apressure-time diagram;

FIG. 3 shows a device for liquefying heavier gases;

FIG. 4 shows the operation of the device shown in FIG. 3 in apressure-time diagram;

FIGS. 5 to 8 show two devices for liquefying lighter gases, for example,hydrogen and helium, with the associated pressure-time diagram in whichthe operation of these devices is explained;

' 4 FIG. 9 shows a further embodiment of a device for liquefying gases.

In FIG. 1, reference numeral 1 denotes a container which contains gasunder high pressure. This container is connected, through a gas inletpipe 2, to the condensation space 3 around the head of a cold-gasrefrigerator 4. The condensation space 8 is in open communication with acontainer 5 which consequently also forms part of the condensationspace. If desired, the condensate may naturally also be stored in thespace 3 itself. The container 5 is provided with an outlet pipe 6 forcondensate which empties in a storage container 7. In the gas inlet pipe2 a cock 8 is provided, while the .outlet pipe 6- for condensatecomprises a cock -9..The cocks-8 and 9 are operated by a control devicewhich in accordance with the pressure in the container 5 or, if desired,in accordance with time, opens or closesthe cocks 8 and 9. The operationof this device will be explained with reference to the time-pressurediagram shown in FIG. 2. The container 1 contains a gas, for example,air, oxygen or nitrogen, under a pressure p which, for example, is from5 to 6 atmospheres. While the cock 9 is closed, the cock 8' is opened.In the spaces 3 and 5 gas enters under high pressure. This high-pressuregas condenses on the cold head of the coldgas refrigerator, thecondensate being received in the container 5. After a given period oftime, or when a given quantity of condensate is available in thecontainer 5, the cock 8 is closed. This consequently happens at point 10in the diagram of FIG. 2. The cold-gas refrigerator 4 goes on supplyingcold, gas condensing on the cold head of the machine from the spaces 3and 5. The temperature in these spaces gradually decreases .while thepressure also decreases. In FIG. 2 the pressure variation is plottedagainst time by the sloping line from point 10. When as a result of thecontinued cooling the pressure in the spaces 3 and 5 has fallen to thepressure p the cock 9 is opened and the condensate can flow into thestorage container 7. The pressure p must be chosen to be suflicientlyhigh above the container pressure so as to retain a' suflicientexcessive pressure for forcing the liquid out of the container 5 intothe container 7. This means that the cooling in the containers3 and Smaynot be continued to such an extent as would be desirable. First .of all,when opening the head 3, the condensate will expand to the head pressurein which again part of the condensate evaporates. Secondly, part of theliquid stored in the container 7 will .evaporate by penetrating heat anddisappear through a blow-off into the atmosphere which consequentlymeans a loss. In order to restrict this loss one would introduce theliquid in the supercooled condition into the container 7, if this werepossible. In that case, the liquid in the container 7 would be heated tosubstantially its boiling point temperature by the penetrating heat.This consequently means that already so much cold is introduced in thehead 3-and container 5 that therewith the insulation losses of thecontainer 7 are overcome. When in the device shown in FIG. 1 thecondensate is to be transferred from the container 5 to the container 7within a permissible period of time, the pressure 11 must be chosen tobe rather high before the removal of the liquid-begins. After the liquidhas been transferred from the container 5 into the container 7, the cock9 is closed and the cock 8 is opened and the pressure in the head 3 andcontainer 5 again increases to the starting pressure p at which pointthe condensation mainly takes place.

According to the invention, the continued cooling may be continued to apressure which is substantially equal to the pressure in the container 7or even to a pressure which lies below the pressure in the container 7,while in addition the time for transferring the condensate from thecontainer 5 to the container 7 is considerably shortened. In the devices.according to the invention both cocks 8 and 9 are opened for thatpurpose during the transfer of the condensate from the container 5 tothe container 7, so that the liquid is forced by the gas under highpressure from the container 5 into the container 7. First of all this isperformed very rapidly and, secondly, supercooled liquid may beforcedinto the container 7.

FIG. 3 shows a device for liquefying heavier gases, for example, air,oxygen and nitrogen. This device again comprises a container 1 for gasunder high pressure, which container is connected through an inlet pipe2, to the condensation space 3 and the container 5. The container 5 isconnected to the storage container 7 through an outlet pipe 6. The inletpipe 2 comprises a cock 8. The outlet pipe 6 comprises a check valve 15in addition to a cock 9. The functions of the cock 9' and the checkvalve 15 may be combined, if desired, in a magneticallyoperated valvewhich operates in the direction of the container 5 as a check valve andcan be lifted electromagnetically from its seating.

The operation of the device shown in FIG. 3 is shown in thetime-pressure diagram of FIG. 4. When the cock 9 in the outlet pipe 6 isclosed, the cock 8 in the inlet pipe 2 is opened. As a result of this,gas under a pressure p can enter the condensation spaces 3 and 5-. Atthis pressure p the cold-gas refrigerator 4 condenses this gas underhigh pressure for a given period of time. After a given period of timeor when a given quantity of condensate is collected in the container 5,the cock '8 is closed. The cold-gas refrigerator 4 continues its coldproduction, the pressure and the temperature in the spaces 3 and 5gradually reducing. The pressure in this case follows the line 16, 17 inthe diagram of FIG. 4. The continued cooling lasts until the pressure inthe spaces 3 and 5 is equal to a pressure p which is lower than thepressure prevailing in the storage container 7. At that instant aquantity of condensate is contained in the continer 5 at a pressure anda temperature of the condensate which are bothlower than the pressureand the temperature of the condensate which is already in the storagecontainer 7. After the pressure p has been reached, the cocks 9 and '8are both opened substantially simultaneously. As a result of this, thepressure in the spaces 3 and 5 rapidly increases. When the pressure inthe space 5 is equal to the pressure in the container 7, the transportof condensate to the container 7 begins. This is indicated in thediagram by the point 18. Now the condensate is' powerfully forced out ofthe space 5 into the space 7 by the gas under high pressure so that thetransport takes place very rapidly and consumes little time. Thepossibility exists that simultaneously with the last of the condensatewhich flows to the container 7 also part of the gas under high pressureflows to the container 7 and then through the blow-off aperture into theatmosphere which would mean a loss. In order to prevent this, a float isprovided opposite to the aperture of the outlet pipe 6 in the container5 which closes the aperture of the outlet pipe 6 as soon as the liquidlevel in the container 5 has fallen below a given value. This float isnot shown in the diagrammatic drawing of FIG. 3 but is visible in thedevice shown in FIG. 9.

Since in the case of lighter-weight gases, for example, hydrogen andhelium, no float of permissible proportions can be used any longer, thedevice shown in FIG. 3 is not particularly suitable for this type ofgas. When as a matter of fact no float' is available, always part ofthese valuable gases will flow to the container 7 .at the end of theforcing-out period of the condensate and be conducted away, which meansa loss. In FIG. 5 a device is shown for liquefying light gases in whichthis loss will not occur or will occur only to a smallextent. In thisfigure corresponding component parts are given the same referencenumerals as in FIG. 3. The only difference with the device shown in FIG.3 is that the inlet pipe 2'is provided with a circulating pipe 19 inwhich a flow resistance 20 constructed as a capillary and a further cock21 are provided.

'The operation of the device shown in FIG. 5 is shown in thetime-pressure diagram of FIG. 6. When the cock 9 in the outlet pipe 6 isclosed, the cock 8 in the inlet pipe 2 is opened. As a result of thishigh-pressure gas can again enter the condensation spaces 3 and 5 out ofthe container 1. The cold-gas refrigerator 4 condenses a quantity of gasfor a given period of time. Then the cock 8 is closed while the cold-gasrefrigerator continues the supply of cold. As a result of this thepressure in the spaces 3' and 5 decreases according to the line 22-23.At point 23 the pressure has decreased to just above the pressure whichprevails in the container 7. At that instant both the cocks 9 in theoutlet pipe 6 and the further cock 21 in the circulating pipe 19 areopened. The capillary 20 is constructed so that through it a quantity ofgas per unit of time can flow which substantially corresponds to thequantity of gas which the cold-gas refrigerator can condense per unit oftime.

This consequently means that by opening the cock 21 the pressure in thecontainer 5 remains substantially equal. So the condensate is forced outof the container 5 at equal pressure. When the condensate hasdisappeared from the container 5 the pressure in this container willdecrease for a moment to the pressure in the container 7, a smallquantity of gas flowing through the container 7'. Then the controldevice closes the cock 9 in the outlet pipe 6 as well as the furthercock 21, while the cock 8 in the inlet pipe for medium is opened againand the pressure in the spaces 3 and 5 increases rapidly to the pressurep at which condensation substantially takes place.

In this device it is not necessary to have a check valve 15 in theoutlet pipe 6 for condensate, because the pressure in the container 7 isalways somewhat lower than the pressure in the container 5. However, tobe quite on the safe side it is possible to have a check valve in theoutlet pipe 6 for the medium.

Instead of the capillary .20, a needle valve may also be used as a flowresistance. In such a valve a very narrow passage may be. adjusted.

A drawback of the device shown in FIG. 5 is that during the continuedcooling the pressure cannot be reduced further than the pressure whichcorresponds to the point 23 of FIG. 6. So in this case no supercooledliquid can be forced into the container 7. In this device, consequently,a certain loss of gas will occur because as a result of insulationlosses a quantity of the condensate evaporates in the container 7. Thisdrawback is avoided in the device shown in FIG. 7. In this device, anauxiliary container 24 is provided in the circulating pipe 19 betweenthe capillary 20 and the further cock 21. In addition, this devicerequires a check valve 15 in the outlet pipe 6. The operation of thisdevice follows from the diagram shown in FIG. 8. First, again the cock 8is opened, as a result of which gas under a pressure p can enter thecondensation spaces 3 and 5 and be condensed there under high pressure.Then the cock 8 is closed and the pressure is reduced, under continuedcooling by means of the coldgas refrigerator 4, to a pressurewhich-corresponds to point 25 shown in FIG. 8. The pressure at point 25is lower than the pressure which prevails in the container 7. After thispressure has been reached, the cock 9 in the outlet pipe 6 is opened,while substantially simultaneously the further cock 21 in thecirculating pipe 19 is opened. As a result of this, the auxiliarycontainer 24 is connected to the condensation spaces 3 and 5. The gas ofhigh pressure in the auxiliary container 24 now enters the spaces 3 and5. As a result of this the pressure in the spaces 3 and 5 rapidlyincreases to a pressure which .corresponds to point 26 in the diagram ofFIG. 8. Thus, this pressure lies somewhat above the pressure in thecontainer 7 so that with this pressure the supercooled liquid can beforced out of the container 5 into the container 7. So now supercooledliquid is transferred to the container 7 in which liquid so much cold ispresent that the insulation losses of the container 7 are greatlyobviated. After removing the remainder of the condensate, a smallquantity of gas will flow to the container 7, while the presare in thecontainer decreases. Then the cock 9 in the utlet pipe 6 is closed andthe cock 8 in the inlet pipe i opened again after which the pressureagain rapidly inreases to the value p and condensation at this highpresure can take place again.

FIG. 9 shows a device for condensing air, nitrogen or xygen; This devicecomprises an inlet pipe for gas to e condensed, which pipe comprises acock 31. The inlet -ipe 30 is connected to an insulated space 32. Inthis space lhich is surrounded by the insulating jacket 33, a number ifsnow separators 34 are arranged around a container '5. Thesnow-separators 34 may be constructed in accord- .nce with theseparators described in French patent speciication 133,695 (Dutch patentspecification 269,432). The eparators 34 are connected to the container35 which, at ts upper side, is connected, through a gas inlet pipe 36, othe condensation space 37 around the cold head of the zold-gasrefrigerator 38. The condensation space 37 is irovided with an outletpipe for condensate 62, the upper :nd of which is connected to acontainer formed by the vall 39 in the container 35. This container 40is in a communicating connection with the separator 34. An overlow pipe60 for conducting away condensate to the con- :ainer 51 is connected tothe container 40. Below the bot :om the walls of the container 35 extendas a perforated iheath-like wall 41. This wall is provided with a bottom12 in which a liquid outlet pipe 43 is connected. This .iquid outletpipe 43 extends through the container 35 upwards and disappears throughthe insulation wall 33 to a storage container not shown. The bottom 42further comprises a number of pipes 44 between which a float 45 isarranged. This float comprises a ball 46 which, when the liquid fallstoo low, can close the aperture of the liquid outlet pipe 43. The floatis provided with a pipe 47 which is open at both ends. With its one end,this pipe empties at the bottom of the float, while the other endprojects upwards so that this end always projects above the liquid inthe container. As a result of this, the pressure inside and outside thefloat will always be equal so that across the wall of the float no largepressure differences will prevail. As a result of this, the float neednot be of a particularly heavy construction. Inside the insulati-on wall33 a wall 48 is provided which separates the space, in which theseparators 34 are arranged, from the space in which the condensatedliquid is received. So in this device there is available an extensiveshallow liquid bath 51, which is desirable in connection with thecontinued cooling in which the liquid is cooled by boiling and thevapour formed is then condensed again on the cold head of the cold-gasrefrigerator 38.

The operation of this device is as follows: When the cock 31 in theinlet pipe 30 for medium is opened, gas under high pressure enters thespace 32 and thence flows to the space 35 through the layers of gauze ofthe separators 34. This is indicated by the arrows p. Since the gauze ofthe separators 34 is strongly cooled by gas which is already condensedin the pipes of the separators, the contaminations which may possibly bein the gas, will be frozen out on this gauze. The gas entering the space35 is drawn into this space through pipe 36 by the subambient pressurewhich prevails in the condensation space 37. The gas condensed in thecondensation space 37 can flow back to the space 40 through the pipe 62.The condensate is first received in the space 40 until a level hasformed which reaches as high as the overflow pipe 60. When the supply ofcondensate is continued, part of this condensate will disappear into theliquid space 51 through the overflow pipe. In the container 40consequently always a given quantity of condensate is available. Sincethis container is connected to the cooling channels of the separators34, condensate also will be present in these channels. As a result ofthe supply of heat, a vapourbubble pumping effect will occur in thesechannels as a result of which the condensate is pumped upwards throughthe channels. In this manner a satisfactory even cooling of the gauzelayers on which the contaminations are frozen out is obtained. After agiven period of time'the cock 31 is closed and the cold-gas refrigeratorreduces by continued cooling the pressure and consequently also thetemperature in the space and thereby also that of the condensate. Thiscooling is continued until the pressure of the condensate is below thepressure which prevails in the storage container so that liquid isobtained which, with respect to the pressure which prevails in thestorage container, is subcooled. Then, simultaneously, the cocks 49 and31 are opened, as a result of which the pressure in the space 35 abovethe liquid rapidly increases to a value which lies considerably abovethe pressure which prevails in the storage container. As a result ofthis high pressure, the liquid is powerfully forced into the liquidoutlet pipe 43. As a result of this a very rapid siphoning over ofliquid to the liquid container takes place. So the coldgas refrigeratorcondenses at the lower pressure only for a comparatively short period oftime. When the liquid in the container 51 falls below a given level, thefloat will close the liquid outlet pipe 43 at a given instant so that itis prevented that high-pressure gas disappears to the storage containerwith the last liquid.

The above device may be used for liquefying helium or hydrogen inaddition to air, nitrogen and oxygen. In that case, only the gas inletpipe must be provided with a circulating pipe parallel to the cook 31 asdescribed in the device shown in FIGS. 5 and 7. The control must then beeffected as is described in FIGS. 6 and 8.

With the method and device according to the invention it has becomepossible to liquefy gases with a good yield and to transfer them to astorage container.

What is claimed is:

p 1. An apparatus for liquefying gas supplied under pressure to areceptacle which is cooled to the condensation temperature of theselected gas comprising a cold source for cooling said receptaclewhereby said gas is condensed, an inlet pipe for said gas supply underpressure, an outlet pipe for said liquefied gas, acont-rollable valve ineach of said inlet and outlet pipes, a storage container, and a controldevice which when the valve in said outlet pipe is closed maintains thevalve in the inlet pipe open for a predetermined period of time, saidcontrol device thereafter closing said valve in the inlet pipe, saidcold source continuing to cool said receptacle and reducing the pressureof said condensate until said pressure is lower than the pressure insaid storage container, and thereafter said control device opening saidvalves in said inlet and outlet pipes when the pressure in thereceptacle is at the said lower pressure whereby the condensate isforced into said storage container by said gas under pressure.

2. An apparatus as claimed in claim 1 wherein said outlet pipe isconnected at one end into said receptacle at a low point thereof, saidone end being directed upwards, and a float being located adjacent tothe opening which when said liquid has fallen below a given level closessaid aperture.

3. An apparatus as claimed in claim 2 wherein the walls of said floatare of a relatively thin construction, a pipe connected to said floatand open at both ends, one end of said pipe emptying at the bottom ofsaid float and extending upwards from said float so that the upper endalways projects above the liquid in the condensation space of saidreceptacle.

4. An apparatus for liquefying gas supplied under pressure to areceptacle which is cooled to the condensation temperature of theselected gas comprising a refrigerator, the cold part of saidrefrigerator being connected to the condensation space in saidreceptacle, an inlet pipe for said gas under pressure connected to saidreceptacle, an outlet pipe for said liquefied gas connected to saidreceptacle, controllable valves in both said inlet and outlet pipes, astorage container for said liquefied gas, a circulating pipe in saidinlet pipe line bypassing the controllable valve therein and having aflow resistance and an additional controllable valve therein, said flowresistance being so constructed that the gases passing through it at thefull pressure difl'erence between said gas inlet pipe and said storagecontainer substantially corresponds to the flow of gas which saidrefrigerator condenses at a pressure which is substantially equal to thepressure in said storage container, and a control device which when thevalve in the outlet pipe is closed maintains the valve in the inlet pipeopen for a given period of time, said control device thereafter closingsaid valve in the inlet pipe and by continued cooling of saidrefrigerator the pressure of the condensate is decreased until it isslightly above the pressure in said storage container, and subsequentlysaid control device opening the valve in said outlet pipe and saidadditional controllable valve when the pressure in the receptacle is atthe pressure slightly above the pressure in the storage container.

5. An apparatus as claimed in claim 4 wherein between said flowresistance and said additional controllable valve a further container islocated, said control device opening said valve in said outlet pipe andsaid additional controllable valve in said circulating pipe only whenthe pressure in said condensation space is lower than the pressure insaid storage container.

6. An apparatus as claimed in claim 4 wherein said flow resistance is acapillary.

References Cited UNITED STATES PATENTS 3,210,952 10/1965 St-rorn 62-403,282,061 11/1966 Van Geuns 6Z37' NORMAN YUDKOFF, Primary Examiner.

V. W. PRETKA, Assistant Examiner.

1. AN APPARATUS FOR LIQUEFYING GAS SUPPLIED UNDER PRESSURE TO ARECEPTACLE WHICH IS COOLED TO THE CONDENSATION TEMPERATURE OF THESELECTED GAS COMPRISING A COLD SOURCE FOR COOLING SAID RECEPTACLEWHEREBY SAID GAS IS CONDENSED, AN INLET PIPE FOR SAID GAS SUPPLY UNDERPRESSURE, AN OUTLET PIPE FOR SAID LIQUEFIED GAS, A CONTROLLABLE VALVE INEACH OF SAID INLET AND OUTLET PIPES, A STORAGE CONTAINER, AND A CONTROLDEVICE WHICH WHEN THE VALVE IN SAID OUTLET PIPE IS CLOSED MAINTAINS THEVALVE IN THE INLET PIPE OPEN FOR A PREDETERMINED PERIOD OF TIME, SAIDCONTROL DEVICE THEREAFTER CLOSING SAID VALVE IN THE INLET PIPE, SAIDCOLD SOURCE CONTINUING TO COOL SAID RECEPTACLE AND REDUCING THE PRESSUREOF SAID CONDENSATE UNTIL SAID PRESSURE IS LOWER THAN THE PRESSURE INSAID STORAGE CONTAINER, AND THEREAFTER SAID CONTROL DEVICE OPENING SAIDVALVES IN SAID INLET AND OUTLET PIPES WHEN THE PRESSURE IN THERECEPTACLE IS AT THE SAID LOWER PRESSURE WHEREBY THE CONDENSATE ISFORCED INTO SAID STORAGE CONTAINER BY SAID GAS UNDER PRESSURE.